Your description mirrors my own experience with the new positive feedback switch on the Torii MK4.Maybe they have the same effect electrically? -> my own theory .

In my system, when the above-mentioned switch is turned off, the sound is dense and centered. When the switch is turned on, the sound appears to be more open and spacious. However, It is sonically more diffused.

Just my own personal preference but I prefer to leave the option turned off.

Interesting, your sense of the feedback circuit. I look forward to hearing it...my MkIV is on the bench!

I am guessing that the feedback and VR change effect on the presentation may be similar, but different. Words are tricky.

Besides the variability of individual tubes of the same type......I think changing VRs is more about the power intensity... I am not an electrical authority by any means, but when I put together what I hear and the idea that the VRs lower or raise the grid voltage of the power tubes, they sound to me like this causes the power tubes to run a little more or less saturated. The effect might be more like when you switch from a warm and full 6922 or 7DJ8 to a more transparent and open sounding one.

Assuming we could start with similarly toned OA3s, OB3, OC3, and OD3s...and if the OA3 makes the amp a little dense and bassy in a system/room, masking the mids, upper mids, and highs a bit, you can definitely enhance the sound stage and clarity with an OB3, OC3, or OD3, each progressively "de-saturating" the sound more. The players generally stay in the same soundstage postion, but the "meat" of each instrument is chilled a bit, leaving the rest of the presentation aspects more space. The mids and upper mids awaken a bit as the low-mids and bass chill a bit. Ambient information takes more space in the sound. The instruments themselves became a bit more spacious and clear, but also the space around them.

So though I imagine the feedback circuit could be described similarly, I would say VR changes cause a less dense, less saturated sound, but no sense of diffusion. Perhaps leaner or bigger describes it in a general way.

I made myself laugh tonight...I said something out-loud that we've probably each thought in our head (well, except for Lon maybe).

I was reading through the MK IV web page for probably the 12th time, and I read the line "the last amp you'll ever want" and I said to myself - Yeah, till the MK V comes out...

Which made me smile, because I'm hoping the Mystery Amp helps me avoid upgrade-itis for a while...then the audio gods smited me for such blasphemy by whispering in my ear "till Steve comes out with an OTL amp in the next few years...." :(

I was startled out of my revere by Brianne banging on the bathroom door asking if I'd died on the toilet ;D

Good evening. Just got my MK 4 this afternoon. It was packed in the Pelican Case, with the tubes packed in a separate box. Installed the tubes and hooked it up. Sound is nice. I still need to get the right speakers to fully appreciate it. Nice to finally have it! Thanks to Decware for answering questions so professionally.

Now that I finally have another Decware amp, my second system is really just now starting in a real way. It is in my small work building and happened sort of organically, and sort of for self preservation!....I mean, ever since I got my Torii MkIII and room tuned in, putting in my old NAD amp when the Torii had to get work was truly painful. Even though that was a nice solid state amp, and I still had it in my tuned room, and hooked in with all the rest of my stuff, cables, vibration stuff, the Zstage, and 944s, the lot.....it just sounded wrong and therefore was not an awakening experience of being "in the music" like the Torii provides here. Well really "awakening" does not cover my feeling from my system...it is like medicine to me it is so comfortable, real and beautiful.

I realized then two main things. One- I fit the profile "Decware....therapy for Audiophiles." And second, I love the natural sound of impeccably presented music so much, my life is simply not as fulfilling without it.

That leads to the self protection part. I have been working up to another Decware amp for a long time. With two, it is unlikely I will be without one!

Now the organic part. I really love my 944s, but in many conversations with ZYGI, starting with my potential interest in his one-off Fuglies...can you figure out the two words that make that name? These speakers were I believe a sort of variation on the HR-1 concept, if I recall, with a nice single driver facing forward and a radial on top...The price was right and I had that niggling for a second pair of speakers for the workshop. One thing led to another, the main thing being Bob's love for the HR-1. So I finally got there and ordered a pair of HR-1s. Luckily he had a couple revelations while making mine that made his already well loved speaker better.

Then of course, I have a few extra cables around from all my explorations there, and loads of tubes, and after years of loving my Zstage (especially with the jupiter caps and two inputs!), then I was finally working toward a Rachel for my second amp....and the CSP had been in my mind for a long time, so I ordered a CSP2+ (that miraculously became a CSP3 for a few of us on the list) at the same time as the Rachel. Now I love the CSP3 in a different way than my modded Zstage.....hmmm two preamp stages I love now.

Unfortunately, in my rooms, the Rachel (though really sweet, especially with the CSP3), after the Torii, it was just not enough. But at this point I am in deep and can't turn around...So for more power....two Rachels and the CSP3, or a MkIV. I am thinking, my god, me being a big tube roller and 2 Rachels needing 4 input tubes, I could not use my great collection of input pairs and would have to buy matched quads. Since 6N1P have never satisfied me, really no current production tubes that I know of either...that could get ugly being a tube freak. Also, after a few talks with Steve, the MkIV made sense.....and a few months later.....a second system!

And that MkIV, with a quad of cryo'd Tungsol KT66, and just a few hours, I know that with burnin and tuning to taste, I am going to love this amp... I am one lucky and happy camper!

Hey Stone. I have thought about very efficient speakers, but I like my speakers, so for now prefer a little power. The MkIV is burning in nicely..maybe 320 hours. About 220-250 was a break through, and I am waiting for the next, but it does sound very good now.

I am still exploring, hunting tube combos for the sound I like most. It is like the MkIII, but not. It uses tubes pretty differently in serious listening. Its tendency here is sort of between the sweet, textural warmth of a Rachel, and how I have my MkIII tuned...linear and transparent with a touch of warmth. It is interesting how it is warm, but also very clear and smooth. For inputs, it makes 6922s sound closer to how PCC88/7DJ8s sound in the MkIII, more open and textural. Definitely a triumph for Steve in my book. I just need more time to know the amp before really talking about it, but I am liking it!